Computational Fluid Dynamics Modeling of Typical Street Split Flow Conditions at Intersections

This project involved the application of computational fluid dynamics (CFD) to model split flow conditions at a typical street intersection. The objective of this project was to study the flow characteristics at street intersections and to determine the optimal location of drain inlets along the minor street in order to maximize the capture of storm water runoff and minimize the potential for flooding of the street. Various tasks were performed to accomplish the project objective including: 1) collection of a topographic database of the street intersection at Kings Row and Wyoming Avenue in Reno, Nevada; 2) development of the framework of a computational model using the mesh generator provided by the Center for Computational Hydroscience and Engineering (CCHE-MESH); 3) performing modeling using the CCHE-Graphical User Interface (GUI) to evaluate flow characteristics at street intersections; and 4) performance of laboratory testing on a full-scale, physical model to validate results of the CCHE-GUI. This document presents the details of the tasks performed along with the analyses and a discussion of the results obtained.;Poorly designed storm water drainage systems along streets may result in periodic flooding which can disrupt normal traffic flow during storm events. The proper design of storm water drainage systems should consider the location, type, and size of the drain inlets as well as the topography of the site (e.g., cross sectional geometry of the street gutters and the longitudinal and transverse slopes of the streets). During this project, computer simulations and laboratory experiments were performed to study the flow characteristics at a typical street intersection in order to identify suitable locations of drain inlets along the streets so as to maximize the capture storm runoff. The topographic data for the street intersection were incorporated into a computer model. Computer simulations were performed to evaluate the characteristics of flow through the intersection under a range of flow conditions. Simulations were also performed to evaluate the effects of varying the longitudinal and transverse (i.e., cross sectional) slopes within the intersection. In most cases, the magnitude of the flow was limited to flows which were confined within the street gutter rather than flows which flooded the entire cross section of the street. The effects of momentum on the flow split at the intersection of two streets were also evaluated using the computer simulations. The inclusion of drain outlets in the computer model enabled the effects of momentum on the flow split and the zone of flow separation to be evaluated.;The results of the computer simulations were compared to the results obtained from the laboratory experiments performed using the physical model. Experiments using the physical model were performed by varying the flows, the longitudinal slopes on both the main channel and the side channel, and the radius of curvature entering the side channel. The zone of flow separation was examined for all cases. The results indicated that the amount of water flowing in the side channel increased as the radius of curvature at the entrance to the side channel increased. The zone of flow separation increased in the longitudinal distance along the curb and transverse distance from the curb as the radius of curvature decreased. The computer simulations demonstrated that placing drain inlets along the main channel just before the diversion into the side channel reduced the downstream flow and velocity, which further decreased the zone of flow separation...